Sun's spectrum is wide and components are strong.

You can't measure distance or speed of Sun by radar directly, because of too much noise.

Sun's own radiation components would mask any possible reflected signal.

But you can use radar to measure distance to Venus at the moment of gretaest elongation, and from right triangle easily calculate distance to Sun.

Speed of Sun is always 15 degrees per hour at any time of a day and any time of a year.

Anyone can go out and measure it whenever they want.

It doesn't depend on shape of Earth.

Wherever you are it is 15 degrees per hour.

Using the method below (while selecting the right side of the picture) the height of Sun was measured to be 5005 kilometers.

Now:

At 30 minutes before equinoctial solar noon in Sao Gabriel, Sun was 7.5 degrees to the east from zenith. It is 5005 km * tan(7.5°) = 658.92 km to the east.

At 30 minutes after equinoctial solar noon in Sao Gabriel, Sun was 7.5 degrees to the west from zenith. It is 5005 km * tan(7.5°) = 658.92 km to the west.

During those 60 minutes Sun travelled 658.92 km + 658.92 km = 1317.84 km.

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In north Brazil there is place named Sao Gabriel de Cachoeira. It is at the Equator.

Noon, March 20, equinox. Sun directly above heads. Shadow lengths zero.

In Maine, USA there is place Wesley, 5005 kilometers north of Sao Gabriel. From there Sun is seen under angle of 45 degrees above horizon, south.

Simple Pythagoras' triangle gives height of the Sun to be 5005 kilometers above Sao Gabriel.

In Argentina there is place Bahia Bustamante at the east coast. From there you see the Sun at 45 degrees above horizon, north.

Bahia Bustamante is 5005 kilometers south from Sao Gabriel. Again, Sun height above Sao Gabriel is 5005 kilometers.

Sun's angular diameter as seen from Sao Gabriel is 0.53 degrees, which makes it to be 2 * 5005 * TAN(0.53 / 2) = 46.3 kilometers in diameter,

or simplified for small angles 5005 * TAN(0.53) = 46.3 kilometers in diameter (again).